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Re: [Dev-C++] get serial port info
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From: Per W. <pw...@ia...> - 2007-12-20 15:19:11
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Yes, strdup() is a nice function to know. If doing the allocation on
program startup, you can normally ignore to release the memory. If doing
it in a loop or not needing the results when your function ends, then you
should do free() on all pointers returned from strdup().
Try to google for "man strdup".
/pwm
On Thu, 20 Dec 2007, Jessica Chen wrote:
> yep.. i will change 4096*256=1M part. that is too big for saving serial
> port info.
>
> the function of strdup is equal to strlen() + malloc() + memcpy()?
> so, i don't need to do memalloc for strSerialList as what i did, since
> strdup() will do?
> is this a correct understanding?
>
>
>
> On Dec 20, 2007 9:23 AM, Per Westermark <pw...@ia...> wrote:
>
> > Now, you are preallocating 4096 bytes for 256 serial ports. That is 1MB of
> > memory. That is not something you want in production code.
> >
> > My change with strdup() would have performed a strlen() + an optimum-sized
> > malloc() + memcpy() for any detected serial ports, i.e. it will end up
> > needing at the most a couple of hundred bytes of memory for the names.
> >
> > /pwm
> >
> > On Thu, 20 Dec 2007, Jessica Chen wrote:
> >
> > > Hi, Per,
> > >
> > > Thanks. I asked my friend to see. He gave me the suggestion. The
> > > RegEnumValue can recognize the com and USB->COM. The problem solved
> > now, I
> > > got the correct result: COM1(com), COM7(usb->com). In front of
> > > RegEnumValue, add:
> > > dwName = sizeof(Name);
> > > dwSizeofPortName = sizeof(szPortName);
> > > So the whole code is as follows (a bug in it: didn't release memalloc,
> > but
> > > doesn't influence the result here).
> > >
> > > #include <windows.h>
> > > #include <stdio.h>
> > > #include <tchar.h>
> > >
> > > int main(void)
> > > {
> > > int z;
> > > char *strSerialList[256];
> > > for (z=0; z<=256; z++)
> > > {
> > > strSerialList[z] = (char*)malloc(4096*sizeof(char));
> > > }
> > > HKEY hKey;
> > >
> > > if( RegOpenKeyEx(HKEY_LOCAL_MACHINE,
> > > TEXT("HARDWARE\\DEVICEMAP\\SERIALCOMM"),
> > > 0,
> > > KEY_READ,
> > > &hKey) != ERROR_SUCCESS)
> > > {
> > > return -1;
> > > }
> > >
> > > int i=0;
> > > CHAR Name[4096];
> > > UCHAR szPortName[4096];
> > > LONG Status;
> > > DWORD dwIndex = 0;
> > > DWORD dwName;
> > > DWORD dwSizeofPortName;
> > > DWORD Type;
> > > dwName = sizeof(Name);
> > > dwSizeofPortName = sizeof(szPortName);
> > >
> > > do
> > > {
> > > dwName = sizeof(Name);
> > > dwSizeofPortName = sizeof(szPortName);
> > > Status = RegEnumValue(hKey, dwIndex++, Name, &dwName, NULL,
> > &Type,
> > > szPortName, &dwSizeofPortName);
> > > printf("Name=%s,szPortName=%s \n", Name, szPortName);
> > > if((Status == ERROR_SUCCESS) )
> > > {
> > > strcpy(strSerialList[i],(char*)szPortName);
> > > //strSerialList[i] = (char*) szPortName;
> > > printf("%s ",strSerialList[i]);
> > > printf("i=%d,dwIndex=%d\n",i,dwIndex);
> > > i++;
> > > }
> > > } while((Status == ERROR_SUCCESS) );
> > > RegCloseKey(hKey);
> > >
> > > printf("\n\n");
> > > for(int j=0;j<i;j++)
> > > {
> > > printf("%s\n",strSerialList[j]);
> > > }
> > >
> > > return 0;
> > > }
> > >
> > >
> > >
> > > On Dec 19, 2007 6:02 PM, Per Westermark <pw...@ia...> wrote:
> > >
> > > > On an old test machine I have, the original code produces:
> > > > COM1
> > > > COM1
> > > > COM1
> > > > COM1
> > > > COM1
> > > > COM1
> > > >
> > > > After adding strdup(), I get:
> > > > COM5
> > > > COM6
> > > > COM7
> > > > COM7
> > > > COM4
> > > > COM1
> > > >
> > > > Are you sure that your change was correct, and that you remembered to
> > > > recompile?
> > > >
> > > > One interesting thing here is that COM7 is printed twice, while my
> > much
> > > > used COM3 is not enumerated.
> > > >
> > > > The two COM7 seems to be a stupid M$ bug with an USB serial adapter :(
> > > >
> > > > /pwm
> > > >
> > > > On Wed, 19 Dec 2007, Jessica Chen wrote:
> > > >
> > > > > Hi, Per,
> > > > >
> > > > > for your second method, i modified like this. i doesn't solve the
> > > > > problem. the result is the same as before.
> > > > > for the first method, i tried to change strSerialList[i] =
> > > > > (char*)(szPortName); to strSerialList[i] =
> > strdup((char*)(szPortName));,
> > > > but
> > > > > it seems doesn't work too. :-(
> > > > >
> > > > > Regards,
> > > > > Jessica
> > > > >
> > > > > do
> > > > > {
> > > > > Status = RegEnumValue(hKey, dwIndex++, Name, &dwName, NULL,
> > > > &Type,
> > > > > szPortName, &dwSizeofPortName);
> > > > > if((Status == ERROR_SUCCESS) || (Status == ERROR_MORE_DATA))
> > > > > {
> > > > > strSerialList[i] = (char*)(szPortName);
> > > > > printf("%s\n",strSerialList[i]);
> > > > > i++;
> > > > > }
> > > > > } while((Status == ERROR_SUCCESS) || (Status ==
> > ERROR_MORE_DATA));
> > > > > RegCloseKey(hKey);
> > > > >
> > > > > On Dec 19, 2007 2:44 PM, Per Westermark <pw...@ia...>
> > wrote:
> > > > >
> > > > > > The test code is buggy. It uses the same buffer to retrieve the
> > device
> > > > > > names, which means that the name will be overwritten.
> > > > > >
> > > > > > A quicky (with a memory leak that doesn't matter here) is to do
> > > > > > strSerialList[i] = strdup((char*)szPortName);
> > > > > >
> > > > > > Another alternative is to print the devices one-by-one directly
> > when
> > > > they
> > > > > > are found.
> > > > > >
> > > > > > /pwm
> > > > > >
> > > > > > On Wed, 19 Dec 2007, Jessica Chen wrote:
> > > > > >
> > > > > > > Name Type Data
> > > > > > > (Default) REG_SZ (value not set)
> > > > > > > \Device\Serial0 REG_SZ COM1
> > > > > > > \Device\U2SPORT1 REG_SZ COM7
> > > > > > >
> > > > > > > if i used on my computer, i can see:
> > > > > > > COM1
> > > > > > > COM1
> > > > > > >
> > > > i> > > when i used my .exe on my colleagues computer.
> > > > > > > he has 2 serial port and 1 usb->serial.
> > > > > > > but we can only see "COM4" for 3 times.
> > > > > > >
> > > > > > > so at least, the code can recognize how many COM on computer,
> > > > whatever
> > > > > > real
> > > > > > > com port or usb-com.
> > > > > > > but cannot read right com port number.
> > > > > > >
> > > > > > >
> > > > > > > On Dec 19, 2007 1:57 PM, Rafael Menezes <so...@gm...>
> > wrote:
> > > > > > >
> > > > > > > > Hi Jessica.
> > > > > > > >
> > > > > > > > Can you, for start, list what is on
> > > > "HARDWARE\\DEVICEMAP\\SERIALCOMM"
> > > > > > in
> > > > > > > > your computer?
> > > > > > > >
> > > > > > > > Regards
> > > > > > > > Rafael
> > > > > > > >
> > > > > > > >
> > > > > > > > On 19/12/2007, Jessica Chen <jes...@gm...> wrote:
> > > > > > > > >
> > > > > > > > > Hi, thanks for ur email, Rafael.
> > > > > > > > >
> > > > > > > > > I researched myself.
> > > > > > > > > I wrote a code. I will list it as follows.
> > > > > > > > > The problem seems it can recognize the real serial com port
> > (Com
> > > > 1
> > > > > > in my
> > > > > > > > > computer, registry).
> > > > > > > > > But on my computer, I have a USB->serial com port (Com 7 in
> > my
> > > > > > > > > computer, registry).
> > > > > > > > > The code cannot recognize the USB->serial com port.
> > > > > > > > > Is there any experienced persons can give any idea about
> > that?
> > > > > > > > >
> > > > > > > > > #include <windows.h>
> > > > > > > > > #include <stdio.h>
> > > > > > > > > #include <tchar.h>
> > > > > > > > >
> > > > > > > > > int main(void)
> > > > > > > > > {
> > > > > > > > > char *strSerialList[256];
> > > > > > > > > HKEY hKey;
> > > > > > > > >
> > > > > > > > > if( RegOpenKeyEx(HKEY_LOCAL_MACHINE,
> > > > > > > > >
> > TEXT("HARDWARE\\DEVICEMAP\\SERIALCOMM"),
> > > > > > > > > 0,
> > > > > > > > > KEY_READ,
> > > > > > > > > &hKey) != ERROR_SUCCESS)
> > > > > > > > > {
> > > > > > > > > return -1;
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > int i=0;
> > > > > > > > > CHAR Name[25];
> > > > > > > > > UCHAR szPortName[25];
> > > > > > > > > LONG Status;
> > > > > > > > > DWORD dwIndex = 0;
> > > > > > > > > DWORD dwName;
> > > > > > > > > DWORD dwSizeofPortName;
> > > > > > > > > DWORD Type;
> > > > > > > > > dwName = sizeof(Name);
> > > > > > > > > dwSizeofPortName = sizeof(szPortName);
> > > > > > > > >
> > > > > > > > > do
> > > > > > > > > {
> > > > > > > > > Status = RegEnumValue(hKey, dwIndex++, Name, &dwName,
> > > > NULL,
> > > > > > > > > &Type,
> > > > > > > > > szPortName, &dwSizeofPortName);
> > > > > > > > > if((Status == ERROR_SUCCESS) || (Status ==
> > > > ERROR_MORE_DATA))
> > > > > > > > > {
> > > > > > > > > strSerialList[i] = (char*)(szPortName);
> > > > > > > > > i++;
> > > > > > > > > }
> > > > > > > > > } while((Status == ERROR_SUCCESS) || (Status ==
> > > > > > ERROR_MORE_DATA));
> > > > > > > > > RegCloseKey(hKey);
> > > > > > > > >
> > > > > > > > > for(int j=0;j<i;j++)
> > > > > > > > > {
> > > > > > > > > printf("%s\n",strSerialList[j]);
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > > return 0;
> > > > > > > > > }
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > On Dec 19, 2007 12:34 PM, Rafael Menezes <so...@gm...>
> > > > wrote:
> > > > > > > > >
> > > > > > > > > > You can send mails. Can you search on google?
> > > > > > > > > >
> > > > > > > > > >
> > > > http://www.google.com.br/search?hl=pt-BR&q=c%2B%2B+com+port&meta =
> > > > > > > > > >
> > > > > > > > > >
> > > > > >
> > > >
> > http://www.google.com.br/search?num=30&hl=pt-BR&q=c%2B%2B+serial+port&meta
> > > > > > > > > > =
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > On 19/12/2007, Jessica Chen <jes...@gm... >
> > wrote:
> > > > > > > > > >
> > > > > > > > > > > is there anyone have the experience for writing code of
> > > > getting
> > > > > > the
> > > > > > > > > > > serial port info from windows?
> > > > > > > > > > > can u give me an sample code?
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > >
> > > >
> > -------------------------------------------------------------------------
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> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > --
> > > > > > > > > > Regards
> > > > > > > > > > Rafael Menezes
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > --
> > > > > > > > Regards
> > > > > > > > Rafael Menezes
> > > > > > >
> > > > > >
> > > > > >
> > > > >
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